This invention relates to horologic instruments and, more particularly, to horologic and chronographic instruments, such as electronic watches and the like, which utilize random timing sources.
Timing sources, such as quartz crystal oscillator circuits, have been widely used in electronic watches and other horologic instruments. The quartz crystals are accurate in producing pulses which are precisely separated in time. The pulses are then counted to generate timekeeping signals which are one second or some other desired fraction of a second apart. The timekeeping signals are then typically utilized to advance an additional set of counters, the output of which drives a display means which indicates relative time, lapsed time or the like. The quartz crystals which are mechanically cut are not identical, and the oscillator circuits do require adjustment; therefore, only a limited but highly acceptable degree of accuracy is attained. Certainly, for applications such as electronic watches, no greater degree of accuracy and, in most instances, a lesser degree of accuracy, is acceptable to the user. On the other hand, quartz crystals are relatively expensive, and it is highly desirable to eliminate this element from electronic watches and other horologic instruments while still providing an acceptable degree of accuracy.
One suggested solution to eliminating the quartz crystal is to replace the quartz crystal oscillator circuits with R-C oscillator circuits. These circuits, although tunable to produce pulses which are precisely separated over a short time period, are very temperature dependent; therefore, an acceptable degree of accuracy is not presently attainable utilizing this approach.
It is, therefore, an object of the present invention to provide improved horologic and chronographic instruments such as electronic watches and the like.
It is another object of the invention to provide electronic watches and other horologic and chronographic instruments which do not require quartz crystals or R-C oscillator circuits as timing sources.
It is still a further object of the invention to provide low-cost electronic horologic and chronographic instruments such as electronic watches and the like.